The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
When manufacturing a scalable phased array antenna for space-based operation, the challenge is fabricating a phased array radiator assembly that is simple to manufacture in large quantities, has low mass, and a low profile, and will meet challenging performance requirements. These requirements include good thermal conductivity through the internal radiator structure, good end-of-life thermal radiative properties (solar absorptance and emittance) at the outer exposed surface of the antenna, and the electrostatic discharge (ESD) grounding requirement for the floating metal elements without compromising the required low RF loss performance. In addition, the materials selected must be capable of resisting degradation due to the natural radiation environment or through atomic oxygen (AO) erosion.
Existing solutions that have good RF properties, for example certain commercially available foams, typically have generally unacceptable thermal conductivity for an application where passive cooling of a phased array antenna is required. As such, pre-existing foams are generally considered to be unacceptable for dissipating heat from the printed wiring board (PWB) modules of a scalable phased array antenna through the radiator assembly of the antenna. Existing solutions using heat pipes and radiators at the edges of the arrays to dissipate heat are heavy and increase the complexity in integration and test for a phased array antenna. Such solutions often significantly increase the cost of manufacture as well.
Many current radiator designs have a gapped radome, which is also termed a “sunshield blanket”, disposed over the antenna aperture above the foam tile assembly. This arrangement is also generally viewed as unacceptable for dissipating heat. To ESD ground floating metal patches, an existing solution is to have a ground pin at the center of each patch. However, this is very difficult and complex to accomplish with foam since manufacturing plated via holes through the foam is not a standard PWB process with proven reliability, and may not be useful for stacked patch configurations.
In general, a primary disadvantage of existing radiator designs for a phased array antenna is that they are highly complex to manufacture. The current solutions are not practical for manufacturing in quantities sufficiently large to make a phased array antenna. Also, the thermal conductivity of presently available foam tile is too low for dissipating heat, while other heat dissipating solutions (e.g., heat pipes) and other grounding methods (e.g., metal pins) add weight. Moreover, flouropolymer based adhesives can be degraded by space radiation effects.